Then as long as the agreement you signed doesn't limit your options you know your choices... give them the idea or run with it yourself. If you give it up you

Then as long as the agreement you signed doesn't limit your options you know your choices... give them the idea or run with it yourself. If you give it up you can always try to negotiate with them first, but be prepared for the possibility that they just walk you to the door or quietly start hunting for your replacement. The only things stopping you from building a competing product are starting from scratch, risk of failure and giving up a steady paycheck. But it sounds like you know all this, so what's the real question? Are you looking for encouragement? Discouragement? If you love the work, like getting paid (and have someone else worry about where the $ are coming from), don't want to take on all the risk of a new startup by yourself then pitch the idea and carry on. If you're feeling cheated because you joined the game too late (series D) to reap any significant financial benefit if an exit event takes place then you can try and negotiate with them, but the idea had better be solid and something they couldn't have just dreamt up and implemented without you. Make sure your valuation of the idea is in line with reality before you try to use it as a bargaining chip.